Overeating and Memory Loss

Older people who overate were more than twice as likely to suffer cognitive impairment than those who ate less.

A study performed by the Mayo Clinic suggests that overeating can more than double the risk of mild cognitive impairment (MCI) in the elderly. While the study is only a preliminary one, it suggests that cutting calories may be a simple way to prevent or slow memory loss as people age.

Mild cognitive impairment is a decline in mental abilities, chiefly memory, that's noticeable but not severe enough to affect the performance of day to day activities. It's sometimes described as an intermediate stage between the expected cognitive decline of normal aging and the more pronounced decline of dementia. People with MCI are at increased risk of developing dementia later on in life.

This type of study can never prove that high calorie consumption caused MCI. But the size of the apparent risk increase (overeaters were almost 2.5 times more likely than low calorie consumers to have cognitive decline) is certainly large enough to make people wonder and will almost surely lead to more detailed studies.

The study was of 1,233 individuals aged 70 to 89 who were taking part in a larger study, the Mayo Clinic Study of Aging. These individuals reported their daily calorie consumption and were then interviewed within one year and tested for MCI. About 13% had MCI (163 people); the other 1,070 did not.

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The subjects were then split into three groups based on their calorie consumption: low, medium and high. The incidence of MCI in the high calorie group was more than double that in the low calorie group. The incidence of MCI in the intermediate calorie group did not differ significantly from that in the low calorie group.

Daily calorie consumption was 600-1,525 for the low calorie group, 1,526-2,142.5 for the medium group and 2,142.5-6,000 for the high calorie group. The researchers observed a dose-response pattern: the higher the number of calories consumed, the greater the odds of MCI.

The study was an observational study: it simply looked at the calorie consumption of a group of people with MCI. This type of study can never prove that high calorie consumption caused MCI. But the size of the apparent risk increase (overeaters were almost 2.5 times more likely than low calorie consumers to have cognitive decline) is certainly large enough to make people wonder and will almost surely lead to more detailed studies.

This isn't the first study to suggest a link between overeating and mental decline. A Swedish study published in 2010 that tracked a younger group of people, average age 42, for 30-40 years found that persons with a higher BMI had significantly lower cognitive ability and significantly greater mental decline over time than their thinner counterparts. This suggests that if overeating really does cause a decline in mental abilities, the time to stop it comes way before the golden years.

The Mayo Clinic study is scheduled to be presented at the 2012 (64th) Annual Meeting of the American Academy of Neurology. The meeting will be held in New Orleans from April 21 to April 28.